1. Field of the Invention
The present invention generally relates to an ergonomically designed seating unit which naturally exercises the body by providing active sitting and, more particularly, to such an ergonomically designed seating unit which employs a fluid-filled, substantially egg-shaped seat which promotes continuous movement of the spine, hips and upper body.
2. Background Discussion
Increasingly, the modern worker is required to spend prolonged periods seated at a workstation. As a result, the potential for back, shoulder and neck problems is considerably increased. This is particularly true when seated in a conventional chair having a rigid seat which, with prolonged use, restricts circulation to the legs and does not allow for constant small movements of the spine, hips and arms. These small movements, herein referred to as "active sitting", are especially beneficial in reducing or preventing pains in the upper body.
It is known to provide conventional office chairs with mechanical arrangements for adjusting the seat height, seat position and backrest position. However, such mechanic devices need periodic servicing, are susceptible to breakage and require a good understanding of ergonomics for proper use. While ergonomically correct backrests, when applied to such office chairs, can substantially eliminate back pain, they do not offer a solution to an even more frequent problem caused by tension in the neck and shoulder area.
One proposed solution to address the above-noted problems associated with the conventional rigid-seat chair is the use of a gymnastics ball as a chair. The ball, typically made of plastic, is well suited for exercising, but does not have the required stability for prolonged use as an office chair, nor the proper dimensions essential for office and/or other workstation labor. Users typically complain of the need to constantly balance their body on the ball which, if not properly addressed, can lead to accidents, such as falling off the ball.
Other prior art seating devices include, for example, U.S. Pat. No. 3,499,682, to Orenstein, which discloses an inflatable chair comprising a plurality of inflatable panels joined together by hinge type connections and mounted to a frame. The arrangement disclosed by Orenstein is not ergonomically suited for office work or other labor requiring prolonged seated periods because the sitting position dictated by the Orenstein chair is not adapted for work at a desk or table. Moreover, horizontal movement of the sitting surface, essential for active sitting, is very limited and insufficient to prevent upper body problems resulting from prolonged sitting. In addition, the panels have to be inflated by air pump or compressor, making the availability of such a device necessary. This invention also does not include the provision of castors, essential for mobility when at work nor can the seat area be detached from the frame and used for other purposes.
U.S. Pat. No. 3,610,689, to Smith, discloses a chair structure, composed of separate inflated members, which are removably secured together. The arrangement is bulky and therefore is not well suited to the work place. Moreover, the upper part of the chair is composed entirely of inflated members, thus lacking the required stability essential for prolonged sitting, especially at the work place where workers perceive instability as being uncomfortable. The seating partition of the Smith invention is made of numerous inflated bags, thereby complicating handling and replacement. Further, these inflatable members must be inflated by a mechanical device, such as an air pump, making the availability of such a device necessary. No castors are available, which limits mobility at work.
U.S. Pat. No. 4,514,010, to Gonzales, discloses an arrangement for the distribution of pressurized fluid to a seat unit. While the areas of the seat unit are pressurized, the movement of the sitting surface is very limited. Only limited vertical movement of the same is possible, horizontal movement, indispensable for active sitting, is not provided for. Moreover, the shape of backrest is not suitable for prolonged use typically encountered at the work place. In addition, no provision is made for application of castors, although these are essential for a working place. Further, the seat area itself cannot be detached from the arrangement and used for other purposes.
British Pat. No. 277,437 issued to Ashmore discloses improvements to chairs, settees and upholstered furniture. This invention expressly restrains horizontal displacement of the sitting surface, a movement indispensable for active sitting. The seat area itself is equipped with springs, therefore, contrary to an inflated seat, does not fit itself exactly to the body shape of the sitting person, so reducing the sensation of ultimate comfort. Moreover, the invention creates a bulky piece of furniture that does not allow for practical usage at the working place. The seat area is connected to the furniture by a guiding device and cannot be used separately.
U.S. Pat. No. 2,779,396, issued to Nail, discloses protective covers for chesterfield chairs, and the like, comprising a central panel and side panels, having slits and adapted to cover the seat, back and arms of a chair, edge portions being united with the central panel. This arrangement does not have the elasticity necessary to cover a balloon seat that changes its size considerably when inflated, or deflated. Should this cover be used for a balloon seat, it would slide over the top of the balloon and the user could slip down from the seat, risking an accident.
Thus, there is a need to provide an improved seating unit that ensures active sitting, optimal sitting position, stability, versatility, variability, mobility and simplicity, yet does not possess the shortcomings of the seating devices presently employed.